A contrite Tatum O’Neal donned a preppy sundress, gold cross and Jackie-O shades and spent her first full day out of the clink at an Alcoholics Anonymous meeting.

The actress trotted out of her Lower East Side apartment building yesterday morning, looking refreshed, rested and revealing multiple tattoos, including a massive inking of her children’s names on her right arm.

“What’s good in what I did?” she said, before climbing into a waiting SUV and whizzing off.

In an exclusive interview with The Post’s Andrea Peyser, O’Neal, 44, said she tried to score drugs on the street because she was depressed about her dog’s death and relationship troubles with architect Ronald Castellano.

“I have the disease of alcoholism. It’s lifelong. I treat it every day by going to my 12-step program,” she said.

She thanked the cops in the Seventh Precinct for “saving” her life.

“I’m eternally grateful, as sort of grim as the situation was, that I didn’t get to do what my disease was telling me to do. I’m still going to get my year on July 10!” she told The Post.

She also said she wanted to help Alan Garcia, 33, the homeless man who was arrested for allegedly selling the drugs to her.

“He’s not a drug dealer. He’s a panhandler who sold drugs,” she said.

O’Neal’s battles with booze and drugs have been well publicized, but she appeared on the mend in recent years. She has a recurring role as Denis Leary’s boozy sister on the cable hit “Rescue Me,” and has a Lifetime movie coming out in August.

Her arrest on Sunday night shocked many of her longtime fans and close friends.

“I have the utmost faith in Tatum,” said Connie Stevens, who directed the star in the upcoming made-for-cable movie, “Saving Grace B. Jones.”

“Tatum is a delight and a part of my family.”

Elisa Petrini, who co-authored the former child star’s sensational autobiography “A Paper Life,” said she is wishing her all the best.

“She seems to be in the right spirits,” said Petrini, who hasn’t spoken to O’Neal recently.